In patients with solid malignancies, serum levels of acute-phase proteins (APP) correlated inversely with delayed cutaneous hypersensitivity (DCH) to dinitrochlorobenzene (DNCB) and serum levels of prealbumin and alpha 2HS-glycoprotein. Serum levels of prealbumin correlated directly with DCH to DNCB. Serum alpha 2 glycoprotein levels correlate directly with DCH and DNCB and lymphocyte reactivity to phytohemagglutinin (PHA). In patients with small cell carcinoma of the lung receiving intensive chemotherapy also randomized to receive placebo or thymosin twice weekly during induction chemotherapy, increased survival occurred in patients receiving thymosin who had low pretreatment T-cell and alpha 2HS-glycoprotein levels. A method for determining percentages of human T- and B-cell lymphocyte subpopulations by cytofluorographic analysis (CFGA) and display of data on a computer-generated three-dimensional grid was developed. The percentages of T and B cells plus specimens from normals when analyzed by CFGA did not differ from the results obtained by light microscopy counting.